Showing papers by "Giuseppe Coppola published in 2000"

Circulating adhesion molecules in humans: role of hyperglycemia and hyperinsulinemia.

Abstract: Background—We assessed the role of glucose and insulin in the regulation of circulating levels of soluble intercellular adhesion molecule-1 (sICAM-1) and vascular adhesion molecule-1 (sVCAM-1) in normal subjects and in patients with type 2 diabetes. Methods and Results—Plasma glucose concentrations were acutely raised in 10 normal subjects and 10 newly diagnosed, complication-free type 2 diabetic patients and maintained at 15 mmol/L for 2 hours. In normal subjects, plasma sICAM-1, but not sVCAM-1, levels rose significantly (P<0.01) at 1 hour and returned to basal values at 2 hours. In another study, octreotide was infused during the hyperglycemic clamp to block the release of endogenous insulin; this prevented the late fall of plasma sICAM-l levels observed in under control clamp conditions. The diabetic patients had plasma sICAM-1 levels significantly higher (P<0.01) than those of the control subjects; plasma sVCAM-1 levels were similar. Both sICAM-l and sVCAM-1 concentrations did not change significantl...

Fast silicon-on-silicon optoelectronic router based on a BMFET device

Abstract: In this paper, a new configuration for an optoelectronic router is presented. The device is composed by a single-mode input waveguide, a two-mode active section where the light steering by means of mode mixing between the fundamental and the first higher order mode is achieved. A terminal Y-branch is placed to separate the output channels. Active modulation is achieved by means of a three-terminal electronic device, which injects and controls the free carrier plasma inside the active region. The usage of a three-terminal device allows extremely fast dynamic response. Switching times of few nanoseconds are obtained together with an average crosstalk of -11 dB.

Feasibility analysis of laser action in erbium-doped silicon waveguides

Abstract: The authors analyze the feasibility of laser action in erbium-doped silicon devices. The recent experimental results on spontaneous light emission at 1.54 /spl mu/m from erbium doped silicon diodes and theoretical calculation on Bragg grating technology are used to evaluate the best scenario performances. The effects of processes-induced errors on the threshold conditions are taken into account. They show that laser action in the Er:Si system is feasible.

Feasibility Analysis of Laser Action in Erbium-Doped

Abstract: — The authors analyze the feasibility of laser action inerbium-doped silicon devices. The recent experimental results onspontaneous light emission at 1.54 m from erbium-doped silicondiodes and theoretical calculation on Bragg grating technology areused to evaluate the best scenario performances. The effects of pro-cesses-inducederrorsonthethresholdconditionsaretakenintoac-count. They show that laser action in the Er:Si system is feasible.Index Terms— Bragg gratings, DBR, semiconductor laser,Si-based erbium laser. I. I NTRODUCTION I N THE LAST decade, silicon photonic integrated circuitshaveattractedaconsiderableinterest[1],[2].Infact,Siisthesemiconductor of choice for the fabrication of advanced elec-tronic devices. Hence, implementation of efficient optical func-tions in Si would allow us to use the mature and low cost SiUltra Large Scale Integration (ULSI) technology for the fabri-cation of integrated optoelectronics circuits. Recent works [2]have shown that infrared light ( m) can be guided,modulated, detected, and emitted in silicon. For several appli-cations, such as intra-chip or chip-to-chip optical interconnects,a key role would certainly be played by a silicon-based, narrowband, fixed frequency, coherent light source. So far, an Si-basedlaser has not been demonstrated. However, it has been recentlyshown [3]–[5] that efficient light emission at 1.54 m can beachieved using Er-doped Si diodes. In this work, we explore thefeasibility of a laser action at 1.54 m using Er-doped Si. In par-ticular, we propose a structure consisting of an Er-doped lightemitting diode, which can be used as an electrically pumped op-tical amplifier operating at 1.54 m, integrated into a rib wave-guide.In order to achieve a laser, a proper resonant optical cavityneeds to be realized. Although the cavity can be fabricated byincreasing the reflectivity of the input and output faces of thewaveguide by means of the deposition of thin films, this so-lution presents several drawbacks. In fact, in order to ensurea high performance optical cavity, any technological processwould hardly guarantee the perfect perpendicularity between

Electrically controlled optoelectronic Y-switch based on a BMFET device

Abstract: We describe a new configuration for an optoelectronic router integrated in a silicon-on-silicon waveguide structure. The device is based on the mode-mixing principle together with the injection-induced phase shift. The structure is composed by a single mode input optical channel waveguide, a two-mode active region and an output Y branch to separate the two output channels. The active region is designed to allow a (pi) shift between the two modes that it supports, by means of a Bipolar Mode Field Effect Transistor, which injects and controls the free carrier plasma inside the active region. By doing so it is possible to steer light from one output channel to the other, when switching from the OFF state to the ON state. The numerical device simulator MEDICI has been used for evaluation of the electrical performances of the device, while different numerical analyses have been exploited to understand its optical behavior. These simulations show optical losses of about 3dB/cm, an overall crosstalk of -10.5 dB and a maximum switching frequency of about 200 MHz.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.